Coating ablating apparatus with coating removal detection

ABSTRACT

A laser-based coating removal apparatus to remove a coating from a surface without damaging the surface. The apparatus comprises a laser source to provide a laser light, a routing element coupled to the laser source and configured to direct the laser light onto a target region of the surface thereby removing the coating from the target region, and a detection element to detect the coating as the coating separates from the target region of the surface. The detection element is able to prevent the surface from being damaged by limiting or eliminating the laser light directed onto the target region after all the coating has been removed. The detection element is able to detect the separation of the coating from the target region by detecting incandescence, acoustic signature, motion, fluorescence and/or chemical properties produced by the separation of the coating from the surface.

RELATED APPLICATIONS

This application claims priority of U.S. provisional application, Ser.No. 61/362,976, filed Jul. 9, 2010, and entitled “Non-Color Sensing forLaser Decoating,” which is incorporated herein by reference.

FIELD OF THE INVENTION

The invention relates to ablating a coating using a laser. Inparticular, the invention relates to a coating ablating apparatus fordetecting the removal of a coating from a surface using a laser toprevent surface damage.

BACKGROUND OF THE INVENTION

Laser-based coating removal systems use pulses of light from high powerlasers to ablate or vaporize the paint or other coating from a surface.Each pulse removes the coating from a small region, typically 0.1 to 100square mm. The laser is pointed to a different area after each pulse,where the removal process is repeated until the entire surface iscleaned. An advantage of lasers for coating removal is that each laserpulse removes a predictable portion of the thickness of the coating, inthe small region impacted by the pulse. This opens the possibility ofselective stripping where, for example, the topcoat could be removed butnot the primer.

A problem with laser de-coating systems is the possibility of damagingthe surface if the stripping process is continued after all the coatingis removed. A particular source of the possible damage is the result ofoverheating the surface due to the absorption of the excess laser lightby the surface after the coating has been removed. Previous techniquesto overcome this problem have relied on measuring the color of thesurface at each point within the laser scan field prior to firing thelaser at that point. However, these techniques do not work well if thedistance and the angle from the laser optics to the substrate varywidely as is the case in many handheld laser de-coating systems onnon-flat surfaces.

SUMMARY OF THE INVENTION

Embodiments of the present invention are directed to a laser-basedcoating removal apparatus to remove a coating from a surface withoutdamaging the surface. The apparatus comprises a laser source to providea laser light, a routing element coupled to the laser source andconfigured to direct the laser light onto a target region of the surfacethereby removing the coating from the target region, and a detectionelement to detect the coating as the coating separates from the targetregion of the surface. The detection element is able to prevent thesurface from being damaged by limiting or eliminating the laser lightdirected onto the target region after all the coating has been removed.The detection element is able to detect the separation of the coatingfrom the target region by detecting incandescence, acoustic signature,motion, fluorescence and/or chemical properties produced by theseparation of the coating from the surface.

In one aspect the present application relates to a laser-based coatingremoval apparatus to remove a coating from a surface. The apparatuscomprises a laser source to provide a laser light, a routing elementcoupled to the laser source and configured to direct the laser lightonto a target region of the surface and a detection element to detectthe coating as the coating separates from the target region of thesurface. In some embodiments, the detection element detects theseparation of the coating from the target region by detecting one ormore coating properties selected from the group consisting of theincandescence, acoustic signature, motion, fluorescence and chemicalproperties. In some embodiments, the routing element transmits a signalrelated the one or more coating properties to the detection element suchthat the detection element is able to detect if the coating isseparating from the target region. In some embodiments, the rate atwhich the laser light is directed onto the surface is adjusted based onwhether the detection element detects that the coating is separatingfrom the target region. In some embodiments, if the detection elementdoes not detect the coating separating from the target region for aperiod, a controller coupled to the detection element decreases the rateat which the laser light is directed onto the target region to apreselected low rate. In some embodiments, the controller is able toadjust the length of the period based on one or more characteristics ofthe target region. In some embodiments, the controller is able to adjustthe level of the low rate based on the one or more characteristics ofthe target region. In some embodiments, if the detection element detectsthe coating separating from the target region while the rate at whichthe laser light is directed onto the target region is equal to the lowrate, the controller increases the rate at which the laser light isdirected onto the target region to a preselected high rate. In someembodiments, the controller is able to adjust the level of the high ratebased on the one or more characteristics of the target region. In someembodiments, the one or more characteristics of the target regioncomprise a temperature of the target region. In some embodiments, thehigh rate is equal to continuous projection of the laser light onto thetarget region and the low rate is equal to none of the laser light beingprojected onto the target region. In some embodiments, the high rate andthe low rate are proportional to each other such that if one of the highor low rate is adjusted, the other rate is also adjusted in proportion.In some embodiments, the detection element divides the target regioninto a plurality of detection areas and if the detection element doesnot detect the coating separating from the target region in one or moreof the detection areas for the period, the controller decreases the rateat which the laser light is directed onto the target region to thepreselected low rate.

A second aspect of the present application is directed to a laser-basedcoating removal system. The system comprises a surface having a coatingand a laser-based removal apparatus comprising a laser source to providea laser light, a routing element coupled to the laser source andconfigured to direct the laser light onto a target region of the surfaceand a detection element to detect the coating as the coating separatesfrom the target region of the surface. In some embodiments, thedetection element detects the separation of the coating from the targetregion by detecting one or more coating properties selected from thegroup consisting of the incandescence, acoustic signature, motion,fluorescence and chemical properties. In some embodiments, the routingelement transmits a signal related the one or more coating properties tothe detection element such that the detection element is able to detectif the coating is separating from the target region. In someembodiments, the rate at which the laser light is directed onto thesurface is adjusted based on whether the detection element detects thatthe coating is separating from the target region. In some embodiments,if the detection element does not detect the coating separating from thetarget region for a period, a controller coupled to the detectionelement decreases the rate at which the laser light is directed onto thetarget region to a preselected low rate. In some embodiments, thecontroller is able to adjust the length of the period based on one ormore characteristics of the target region. In some embodiments, thecontroller is able to adjust the level of the low rate based on the oneor more characteristics of the target region. In some embodiments, ifthe detection element detects the coating separating from the targetregion while the rate at which the laser light is directed onto thetarget region is equal to the low rate, the controller increases therate at which the laser light is directed onto the target region to apreselected high rate. In some embodiments, the controller is able toadjust the level of the high rate based on the one or morecharacteristics of the target region. In some embodiments, the one ormore characteristics of the target region comprise a temperature of thetarget region. In some embodiments, the high rate is equal to continuousprojection of the laser light onto the target region and the low rate isequal to none of the laser light being projected onto the target region.In some embodiments, the high rate and the low rate are proportional toeach other such that if one of the high or low rate is adjusted, theother rate is also adjusted in proportion. In some embodiments, thedetection element divides the target region into a plurality ofdetection areas and if the detection element does not detect the coatingseparating from the target region in one or more of the detection areasfor the period, the controller decreases the rate at which the laserlight is directed onto the target region to the preselected low rate.

Another aspect of the present application is directed to a laser-basedmethod of removing a coating from a surface. The method comprisesactivating a laser source to provide a laser light, directing the laserlight onto a target region of the surface with a routing element anddetecting if the coating is separating from the target region of thesurface with a detection element. In some embodiments, the detectionelement detects the separation of the coating from the target region bydetecting one or more coating properties selected from the groupconsisting of the incandescence, acoustic signature, motion,fluorescence and chemical properties. The method further comprisestransmitting a signal related the one or more coating properties withthe routing element to the detection element such that the detectionelement is able to detect if the coating is separating from the targetregion. The method further comprises adjusting the rate at which thelaser light is directed onto the surface based on whether the detectionelement detects that the coating is separating from the target region.The method further comprises decreasing the rate at which the laserlight is directed onto the target region to a preselected low rate ifthe detection element does not detect the coating separating from thetarget region for a period. The method further comprises adjusting thelength of the period based on one or more characteristics of the targetregion. The method further comprises adjusting the level of the low ratebased on the one or more characteristics of the target region. Themethod further comprises increasing the rate at which the laser light isdirected onto the target region to a preselected high rate if thedetection element detects the coating separating from the target regionwhile the rate at which the laser light is directed onto the targetregion is equal to the low rate. The method further comprises adjustingthe level of the high rate based on the one or more characteristics ofthe target region. In some embodiments, the one or more characteristicsof the target region comprise a temperature of the target region. Insome embodiments, the high rate is equal to continuous projection of thelaser light onto the target region and the low rate is equal to none ofthe laser light being projected onto the target region. In someembodiments, the high rate and the low rate are proportional to eachother such that if one of the high or low rate is adjusted, the otherrate is also adjusted in proportion. The method further comprisesdecreasing the rate at which the laser light is directed onto the targetregion to the preselected low rate if the detection element does notdetect the coating separating from the target region in one or more of aplurality of detection areas for the period, wherein the detection areaseach comprise a portion of the target region. The method furthercomprises adjusting the size of the detection areas based on thecharacteristics of the surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates an exemplary block diagram of the coating removalsystem having a common detection path according to some embodiments.

FIG. 1B illustrates an exemplary block diagram of the coating removalsystem having a separate detection path according to some embodiments.

FIG. 2A illustrates a more detailed diagram of an exemplary blockdiagram of the coating removal system having a common detection pathaccording to some embodiments.

FIG. 2B illustrates a more detailed diagram of an exemplary blockdiagram of the coating removal system having a separate detection pathaccording to some embodiments.

FIG. 3 illustrates a flow chart of a method of removing a coating from asurface according to some embodiments.

Embodiments of the coating removal device are described relative to theseveral views of the drawings. Where appropriate and only whereidentical elements are disclosed and shown in more than one drawing, thesame reference numeral will be used to represent such identicalelements.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

Embodiments of the present invention are directed to a laser-basedcoating removal apparatus to remove a coating from a surface withoutdamaging the surface. The apparatus comprises a laser source to providea laser light, a routing element coupled to the laser source andconfigured to direct the laser light onto a target region of the surfacethereby removing the coating from the target region, and a detectionelement to detect the coating as the coating separates from the targetregion of the surface. The detection element is able to prevent thesurface from being damaged by limiting or eliminating the laser lightdirected onto the target region after all the coating has been removed.The detection element is able to detect the separation of the coatingfrom the target region by detecting incandescence, acoustic signature,motion, fluorescence and/or chemical properties produced by theseparation of the coating from the surface.

Reference will now be made in detail to implementations of thelaser-based coating removal apparatus as illustrated in the accompanyingdrawings. The same reference indicators will be used through thedrawings and the following detailed description to refer to the same orlike parts. In the interest of clarity, not all of the routine featuresof the implementations described herein are shown and described. It willalso be appreciated that in the development of any such actualimplementation, numerous implementation-specific decisions be made toachieve the developer's specific goals, such as compliance withapplication and business related constraints, and that these specificgoals will vary from one implementation to another and from onedeveloper to another. Moreover, it will be appreciated that such adevelopment effort might be complex and time-consuming, but wouldnevertheless be a routine undertaking of engineering for those ofordinary skill in the art having the benefit of this disclosure.

FIG. 1A illustrates an exemplary block diagram of a coating removalsystem 100 using a common path according to some embodiments. Thecoating removal system 100 comprises a laser source 102, a routingelement 104, a detection element 106 and a controller 108 for removing acoating 98 from a surface 99. In some embodiments, the system 100comprises one or more additional laser sources 102, routing elements104, detection elements 106 and/or controllers 108. The laser source 102is able to comprise one or more lasers. Alternatively, the laser source102 is able to comprise other components capable of outputting laserlight 97 (see FIGS. 2A and 2B) as are well known in the art. The lasersource 102 is coupled to routing element 104 such that laser light 97output by the laser source 102 is received by the routing element 104such that the routing element 104 is able to manipulate and direct/routethe laser light 97 onto the desired portion of the surface 99 having thecoating 98 to be removed. Specifically, the routing element 104 isoptically coupled to the surface 99/coating 98 such that the routingelement 106 is able to direct the laser light 97 received from the lasersource 102 onto the surface 99 to effectuate the removal of the coating98 from the surface 99.

As shown in FIG. 1A, the routing element 104 is also coupled to theinput of the detection element 106 such that one or more of theproperties of the surface 99 and/or the coating 98 (as the coating 98 isbeing removed from the surface 99), are able to be transmitted to thedetection element 106 by the routing element 104. In other words, boththe laser source 102 and the detection element 106 are able to use acommon path through the routing element 104 to access the surface 99and/or coating 98. For example, components of the routing element 104used for routing the laser light 97 to the surface 99 are able to beused to receive incandescent light from the coating 98 caused by theremoval of the coating 98 from the surface 99 and transmit that receivedincandescent light (or a signal 96 corresponding to the incandescentlight (see FIG. 2A)) to the detection element 106. Alternatively,signals 96 corresponding to other properties of the surface 99 and/orcoating 98 are able to be transmitted to the detection element 106 bythe routing element 104 such as acoustic signature, motion, fluorescenceand other detectable chemical properties of the surface 99/coating 98 asare well known in the art. The detection element 106 is able to receivethe one or more signals of properties 96 corresponding to the surface 99and/or coating 98 from the routing element 104 and determine if thecoating 98 is currently separating from the surface 99. Specifically,the detection element 106 is able to determine if the coating 98 iscurrently separating from the surface 99 by determining if the detectedproperties exceed a preselected threshold indicating that separation iscurrently occurring in the detected area of the surface 99.

The controller 108 is coupled to the detection element 106 and the lasersource 102 such that the controller 108 is able to control the operationof the laser source 102 based on the output received from the detectionelement 106. Specifically, the controller 108 is able to adjust the rateand/or intensity at which the laser light 97 is output by the lasersource 102 based on whether the output of the detection element 106indicates that the coating 98 is currently being removed or if theremoval of the coating 98 is no longer being detected. As a result,during the process of removing the coating 98 from the surface 99, thesystem 100 is able to determine when the coating 98 is no longer beingremoved from the surface 99 (e.g. all the coating 98 has been removed)and lower or raise the rate and/or intensity of the laser light 97output onto the surface 99 accordingly in order to efficiently removethe coating 98 while preventing the surface 99 from being damaged fromthe laser light 97. The controller 108 is able to comprise variousdesigns of one or more electronic devices well known in the art whichare not discussed herein for the sake of brevity. In some embodiments,one or more of the components of the coating removal system 100 areincorporated into a single coating removal apparatus. Alternatively, thecomponents of the coating removal system 100 are able to comprisemultiple devices.

FIG. 1B illustrates an exemplary block diagram of the coating removalsystem 100′ having a separate detection path according to somealternative embodiments. The system 100′ shown in FIG. 1B issubstantially similar to the system 100 except for the differencesdescribed herein. Specifically, the detection element 106 of the system100′ is coupled directly to the surface 99 and/or the coating 98 forminga separate detection path instead of coupling through the routingelement 104. The manner in which the detecting element 106 is coupled tothe surface 99/coating 98 depends on the one or more types of surface99/coating 98 properties used to determine if the coating 98 iscurrently being removed. For example, if the incandescence produced bythe removed coating 98 is to be detected, the detecting element 106 isoptically coupled to the surface 99/coating 98. Alternatively, othermanners of coupling or combination of manners of coupling are able to beused as are well known in the art in order to detect one or more ofincandescence, acoustic signature, motion, fluorescence and otherdetectable chemical properties of the surface 99/coating 98. As aresult, the detection element 104 is able to directly monitor andreceive signals 96 (see FIG. 2B) from the surface 99 and/or coating 98as the system 100′ is operating and output to the controller 108 whetherthe removal of the coating 98 is currently detected. Alternatively, thedetection element 106 is able to be coupled to both the routing element104 and the surface 99/coating 98 such that the detection element 106 isable to receive signals 96 corresponding to the properties of thecoating 98 and/or surface 99 as the coating 98 is removed from thesurface 99 from the surface 99/coating 98 directly, via the routingelement 104 or both.

FIG. 2A illustrates a more detailed diagram of a coating removal system100 using a common path according to some embodiments. As shown in FIG.2A, the routing element 104 comprises a beam splitter 202, focusingoptics 204 and scanning optics 206. The focusing optics 204 receive andfocus light passing through the beam splitter 202 from the light source102 to the scanning optics 206 which align and focus the laser light 97onto the coating/surface 98, 99. The scanning optics 206 also receivesignals 96 (e.g. incandescent light from gaseous removed coating 98)that are routed from the scanning optics 206 to the beam splitter 202(via the focusing optics 204). The beam splitter 202 receives thesignals 96 and routes the signals 96 to the detection element 106. As aresult, the routing element 104 is able to utilize the common path tosimultaneously route the laser light 97 onto the surface/coating 98, 99and receives/transmits signals 96 (e.g. detected coating 98 gaseousincandescence upon removal) related to one or more properties of theremoval of the coating 98 from the surface 99 to the detection element106 for determining the state of the coating removal process. It isunderstood that the routing element 104 is able to comprise less or morecomponents for routing the laser light 97 and/or transmitting thesurface/coating signals 96 to the detection element 106 as are wellknown in the art. For example, in some embodiments, the routing element104 is able to comprise audio, electrical and/or chemical detection andtransmission elements enabling the routing element 104 to use the commonpath to simultaneously route, in addition to light, audio, electrical,chemical and/or other types of signals 96 related to the properties ofthe removal of the coating 98 from the surface 99 to the detectionelement 106.

As also shown in FIG. 2A, the detection element 106 comprises an inputinterface 208, a signal detector 210 and a comparator 212. In someembodiments, the input interface 208 comprises an input lens forreceiving a light signal 96. Alternatively, the input interface 208 isable to comprise one or more other components for receiving audio,visual, electrical, chemical and other types of signals 96 as are wellknown in the art. In some embodiments, the signal detector 210 is aphotosensitive device such as a photodiode for receiving a light signal.Alternatively, the signal detector 210 is able to be other detectingdevices such as a microphone or other types of detectors able to detectone or more of incandescence, acoustic signature, motion, fluorescenceand other detectable chemical properties of the surface 99/coating 98.For example, in order to detect an acoustic signature of the separatingcoating 98, the signal detector 210 is able to comprise a microphone forconverting the received audio signal to a desired corresponding signaland a filter to separate sounds generated from the separated coating 98from other noise. In some embodiments, the comparator 212 comprises anamplifier for comparing the signal 96 to a threshold voltage.Alternatively, the comparator 212 is able to comprise other componentsfor comparing a received signal 96 to a reference as are well known inthe art.

In operation, the input interface 208 receives the signals 96 from therouting element 104 and transmits the signals 96 to the signal detector210. The signal detector 210 converts the received signal 96 to adesired corresponding signal and transmits the corresponding signal tothe comparator 212 which determines if the received corresponding signalindicates that the coating 98 is currently being removed from thesurface 99. In some embodiments, the comparator 212 makes thisdetermination by determining if a voltage of the corresponding signalexceeds a predetermined threshold voltage. Alternatively, the comparator212 is able to make the determination based on voltage and/or one ormore other properties of the corresponding signal as are well known inthe art. As a result, the detection element 106 is able to output adetection signal to the controller 108 indicating whether the coating 98is currently being detected as being currently removed from the surface99. It is understood that the detection element 106 is able to compriseless or more components for determining if the surface/coating signals96 indicate that the coating 98 is currently being removed from thesurface 99 as are well known in the art. For example, the inputinterface 208 is able to be omitted and the signal 96 is able to bereceived directly by the signal detector 210.

As described above in relation to FIG. 1A, the controller 108 adjuststhe rate and/or intensity at which the laser light 97 is output by thelaser source 102 based on whether the coating 98 is currently beingremoved or if the removal of the coating 98 is no longer being detected.In some embodiments, the controller 108 increases the intensity and/orrate/frequency at which the light 97 is output from a predetermined lowlevel to a predetermined high level when the removal of the coating 98is detected. For example, the controller 108 is able to increase therate and/or intensity from 0 or 1% of the normal rate/intensity to 100%of the normal rate/intensity upon detecting the removal of the coating98. Alternatively, the low and high levels are able to be otherpercentages of the normal rate/intensity or preselected rate/intensityvalues. Alternatively, the rate and/or intensity is able to be adjustedgradually/incrementally by the controller 108. In some embodiments whereboth rate and intensity values are adjusted, the rate value andfrequency value are able to be adjusted to different levels dependentlyor independently.

Similarly, in some embodiments, the controller 108 decreases theintensity and/or rate at which the light 97 is output from thepredetermined high level to the predetermined low level when the removalof the coating 98 is not detected for a period. In some embodiments, theperiod is 50 milliseconds. Alternatively, other periods arecontemplated. In some embodiments, the period, predetermined high leveland/or predetermined low level are able to be adjusted based on thecharacteristics of the surface 99. For example, if the rate of change ofthe surface temperature is low, the surface temperature is low and/orthe surface is able to endure high temperatures before becoming damaged,the period and/or low level is able to be increased to reflect theresistance to damage of the surface 99. As a result, during the processof removing the coating 98 from the surface 99, the system 100 is ableto determine when the coating 98 is no longer being removed from thesurface 99 (e.g. all the coating 98 has been removed) and lower the rateand/or intensity of the laser light 97 output onto the surface 99 inorder to prevent the surface 99 from being damaged from the laser light97.

FIG. 2B illustrates a more detailed diagram of a coating removal system100′ with a separate detection path according to some embodiments. Thesystem 100′ shown in FIG. 2B is substantially similar to the system 100shown in FIG. 2A except for the differences described herein.Specifically, the input interface 208 of the detection element 106 ofthe system 100′ is coupled directly to the surface 99 and/or the coating98 forming a separate detection path instead of coupling through therouting element 104. As described above in relation to FIG. 1B, themanner in which the input interface 208 is coupled to the surface99/coating 98 depends on the one or more types of surface 99/coating 98properties used to determine if the coating 98 is currently beingremoved. For example, if the incandescence produced by the removedcoating 98 is to be detected, the input interface 208 is able tocomprise a lens that is optically coupled to the surface 99/coating 98.Alternatively, other manners of coupling or combination of manners ofcoupling are able to be used as are well known in the art in order todetect one or more of incandescence, acoustic signature, motion,fluorescence and other detectable chemical properties of the surface99/coating 98. As a result, the detection element 104 is able todirectly monitor and receive signals 96 from the surface 99 and/orcoating 98 as the system 100′ is operating and output the detectionsignal to the controller 108 indicating whether the removal of thecoating 98 is currently detected. In some embodiments, the inputinterface 208 is able to be coupled to both the routing element 104 andthe surface 99/coating 98 such that the detection element 106 is able toreceive signals 96 corresponding to the properties of the coating 98and/or surface 99 as the coating 98 is removed from the surface 99 fromthe surface 99/coating 98 directly, via the routing element 104 or both.In some embodiments, the input interface 208 is able to be omitted andinstead the signal detector 210 is able to be coupled directly to thesurface 99/coating 98, via the routing element 104 or both.

In some embodiments, the detection element 104 is able to define aplurality of detection areas, which are a fraction of a target area ofthe surface 99/coating 98 contacted by the laser light 97 during theremoval process, in order to guard against the situation where one areof the target surface is being damaged even though coating removal isstill being detected in another part of the target area. Specifically,using the smaller detection areas, the detection element 104 to able toindividually detect whether coating removal is absent in one or more ofthe detection areas and lower the laser rate and/or intensity eventhough coating removal is still being detected in another detection area(i.e. another part of the target area). Thus, by refining thesize/number of detection areas defined within the target area, thesystem 100, 100′ is able to minimize the chance that current coatingremoval at one end of the target area is able to occur while another endof the target area is being damaged. In some embodiments, the system100, 100′ is also able to reduce the risk of damage by enabling a userto selectively choose the one or more types of properties of the surface99/coating 98 the system 100, 100′ should detect in order to determineif the coating 98 is currently being removed. For example, a user isable to select one or a combination of light, audio and chemicalproperties to detect based on what is determined as the most accurateindicator for a particular surface 99/coating 98. Thus, the system 100,100′ is able to be customized for each job in order to most effectivelyreduce the risk of surface damage.

FIG. 3 illustrates a flow chart of a method of removing a coating from asurface according to some embodiments. The controller 108 activates thelaser source 102 and begins firing the laser light 97 at the low rateand/or intensity onto the target region of the surface at the step 302.Alternatively, the controller 108 is able to cause the laser source 102to begin firing at the high rate and/or intensity as described in step306 below. The detection element 106 detects if the coating 98 iscurrently separating from the target region of the surface 99, whereinthe system 100, 100′ returns to step 302 (firing at the lowrate/intensity) if removal is not detected and advances to step 306 ifremoval is detected at the step 304. In some embodiments, the detectionelement 106 detects the separation of the coating 98 from the targetregion by detecting one or more coating properties selected from thegroup consisting of the incandescence, acoustic signature, motion,fluorescence and chemical properties. In some embodiments, a signal 96related to the one or more coating properties is transmitted by therouting element 104 to the detection element 106 such that the detectionelement 106 is able to detect if the coating 98 is separating from thetarget region. The controller 108 increases the rate and/or intensity atwhich the laser light 97 is directed onto the target region to apreselected high rate at the step 306. In some embodiments, the level ofthe preselected high rate is adjusted based on the one or morecharacteristics of the target region. In some embodiments, the one ormore characteristics of the target region comprise a temperature of thetarget region. The detection element 106 detects if the coating 98 iscurrently separating from the target region of the surface 99, whereinthe system 100, 100′ returns to step 306 (firing at the highrate/intensity) if removal is detected and advances to step 310 ifremoval is not detected at the step 308. The controller 108 determinesif the detection element 106 has not detected the coating 98 separatingfrom the target region for a predefined period, wherein if the periodhas not elapsed the system 100, 100′ returns to step 306 (firing at thehigh rate/intensity) and if the period has elapsed the system 100, 100′returns to step 302 (firing at the low rate/intensity) at the step 310.

In some embodiments, the length of the period is adjusted automaticallyby the controller 108 or by a user based on one or more characteristicsof the target region. In some embodiments, the level of the low rate isadjusted automatically by the controller 108 or by a user based on theone or more characteristics of the target region. In some embodiments,the high rate is equal to continuous projection of the laser light 97onto the target region and the low rate is equal to none of the laserlight 97 being projected onto the target region. In some embodiments,the high rate and the low rate are proportional to each other such thatif one of the high or low rate is adjusted, the other rate is alsoadjusted in proportion. In some embodiments, one or more detection areasare defined and the rate at which the laser light 97 is directed ontothe target region is decreased to the preselected low rate if thedetection element 106 does not detect the coating 98 separating from thetarget region in one or more of the detection areas for the period. Insome embodiments, the detection areas each comprise a portion of thetarget region. In some embodiments, the size of the detection areas areadjusted automatically by the system 100, 100′ or by a user based on thecharacteristics of the surface 99 and/or the coating 98. Accordingly,the coating removal system 100, 100′ is able to minimize the risk ofdamage to the surface 99 by dynamically detecting if the coating 98 isno longer being removed from the surface 99 such that the surface 99 isbeing directly subjected to damaging laser light 97.

Thus, it is clear that the coating removal system described herein hasnumerous advantages. Specifically, the coating removal system is able toefficiently remove coatings on a surface without damaging the surface bydetecting when all the coating has been removed. Further, this damageprevention is able to effectively operate even if the distance and theangle from the laser optics to the substrate vary widely as is the casein many handheld laser de-coating systems on non-flat surfaces.Moreover, the damage prevention aspect is able to be dynamicallyadjusted based on the characteristics of the surface and/or theproperties of the coating and its separation from the surface. As aresult, the coating removal system is able to save energy and cost whilestill ensuring that no damage is caused to the surface by the system.

The present invention has been described in terms of specificembodiments incorporating details to facilitate the understanding of theprinciples of construction and operation of the invention. Suchreference herein to specific embodiments and details thereof is notintended to limit the scope of the claims appended hereto. It will beapparent to those skilled in the art that modifications may be made inthe embodiment chosen for illustration without departing from the spiritand scope of the invention.

1. A laser-based coating removal apparatus to remove a coating from asurface, the apparatus comprising: a. a laser source to provide a laserlight for removing the coating from a target region of the surface; b. arouting element coupled to the laser source and configured to direct thelaser light onto a target region of the surface; c. a detection elementto detect the coating as the coating separates from the target region ofthe surface by inputting a signal received from the surface at thetarget region; and d. a controller configured to adjust a current firingrate of the laser light based on the signal received from the surface atthe target region, wherein if the detection element detects that thecoating has separated from the surface in the target region for aperiod, the controller coupled to the detection element decreases anamount of energy per second directed onto the target region by the laserlight from a non-zero preselected high value to a non-zero preselectedlow value and further wherein the controller is able to adjust a lengthof the period based on one or more characteristics of the surface in thetarget region.
 2. The apparatus of claim 1 wherein the signal comprisesdata indicating one or more properties selected from the groupconsisting of the incandescence, acoustic signature, motion,fluorescence and chemical properties.
 3. The apparatus of claim 2wherein the routing element receives the signal from the surface andtransmits the signal to the detection element such that the detectionelement is able to detect if the coating has separated from the surface.4. The apparatus of claim 1 wherein an amount of energy per seconddirected onto the surface by the laser light is adjusted from a firstnon-zero amount to a second non-zero amount different than the firstnon-zero amount based on whether the detection element detects that thecoating has separated from the surface in the target region.
 5. Theapparatus of claim 1 wherein if the detection element does not detectthe coating separating from the target region for the period, thecontroller coupled to the detection element decreases the rate at whichthe laser light is directed onto the target region to the non-zeropreselected low value.
 6. The apparatus of claim 5 wherein thecontroller is able to adjust the length of the period based on the oneor more properties of the surface in the target region.
 7. The apparatusof claim 6 wherein the controller is able to adjust the level of thenon-zero preselected low value based on the one or more properties ofthe surface in the target region.
 8. The apparatus of claim 7 wherein ifthe detection element detects the coating has not yet separated from thesurface in the target region for a duration while the amount of energyper second directed onto the target region by the laser light is equalto the non-zero preselected low value, the controller increases theamount of energy per second directed onto the target region by the laserlight to the non-zero preselected high value.
 9. The apparatus of claim8 wherein the controller is able to adjust the level of the non-zeropreselected high value based on the one or more properties of thesurface in the target region.
 10. The apparatus of claim 9 wherein theone or more properties of the surface in the target region comprise atemperature of the surface in the target region.
 11. The apparatus ofclaim 10 wherein the non-zero preselected high value is equal to amaximum amount of energy per second produced when the laser light has amaximum intensity and frequency and the non-zero preselected low valueis equal to a minimum amount of energy per second produced when thelaser light has a non-zero minimum intensity and frequency.
 12. Theapparatus of claim 11 wherein the non-zero preselected high value andthe non-zero preselected low value are proportional to each other suchthat if the non-zero preselected high or value rate is adjusted, thenon-zero preselected low value is adjusted in proportion to the non-zeropreselected high value and if the non-zero preselected low value isadjusted, the non-zero preselected high value is adjusted in proportionto the non-zero preselected low value.
 13. The apparatus of claim 12wherein the detection element divides the target region into a pluralityof detection areas.
 14. A laser-based coating removal system comprising:a. a surface having a coating; and b. a laser-based removal apparatuscomprising: i. a laser source to provide a laser light for removing thecoating from a target region of the surface; ii. a routing elementcoupled to the laser source and configured to direct the laser lightonto a target region of the surface; iii. a detection element to detectthe coating as the coating separates from the target region of thesurface by inputting a signal received from the surface at the targetregion; and iv a controller configured to adjust a current firing rateof the laser light based on the signal received from the surface at thetarget region, wherein if the detection element detects that the coatinghas separated from the surface in the target region for a period, thecontroller coupled to the detection element decreases an amount ofenergy per second directed onto the target region by the laser lightfrom a non-zero preselected high value to a non-zero preselected lowvalue and further wherein the controller is able to adjust a length ofthe period based on one or more characteristics of the surface in thetarget region.
 15. The system of claim 14 wherein the signal comprisesdata indicating one or more coating properties selected from the groupconsisting of the incandescence, acoustic signature, motion,fluorescence and chemical properties.
 16. The system of claim 15 whereinthe routing element receives the signal from the surface and transmitsthe signal to the detection element such that the detection element isable to detect if the coating has separated from the surface.
 17. Thesystem of claim 14 wherein an amount of energy per second directed ontothe surface by the laser light is adjusted from a first non-zero amountto a second non-zero amount different than the first non-zero amountbased on whether the detection element detects that the coating hasseparated from the surface in the target region.
 18. The system of claim14 wherein if the detection element does not detect the coatingseparating from the target region for the period, the controller coupledto the detection element decreases the rate at which the laser light isdirected onto the target region to the non-zero preselected low value.19. The system of claim 18 wherein the controller is able to adjust thelength of the period based on the one or more properties of the surfacein the target region.
 20. The system of claim 19 wherein the controlleris able to adjust the level of the non-zero preselected low value basedon the one or more properties of the surface in the target region. 21.The system of claim 20 wherein if the detection element detects thecoating has not yet separated from the surface in the target region fora duration while the amount of energy per second directed onto thetarget region by the laser light is equal to the non-zero preselectedlow value, the controller increases the amount of energy per seconddirected onto the target region by the laser light to the non-zeropreselected high value.
 22. The system of claim 21 wherein thecontroller is able to adjust the level of the non-zero preselected highvalue based on the one or more properties of the surface in the targetregion.
 23. The system of claim 22 wherein the one or more properties ofthe surface in the target region comprise a temperature of the surfacein the target region.
 24. The system of claim 23 wherein the non-zeropreselected high value is equal to a maximum amount of energy per secondproduced when the laser light has a maximum intensity and frequency andthe non-zero preselected low value is equal to a minimum amount ofenergy per second produced when the laser light has a non-zero minimumintensity and frequency.
 25. The system of claim 24 wherein the non-zeropreselected high value and the non-zero preselected low value areproportional to each other such that if the non-zero preselected high orvalue rate is adjusted, the non-zero preselected low value is adjustedin proportion to the non-zero preselected high value and if the non-zeropreselected low value is adjusted, the non-zero preselected high valueis adjusted in proportion to the non-zero preselected low value.
 26. Thesystem of claim 25 wherein the detection element divides the targetregion into a plurality of detection areas. 27-40. (canceled)